lecture 12 guest lecture.docx

Lecture 12:
- antimicrobial: substance that kills or inhibits the growth of bacteria, fungi, protozoa, or viruses
 either kill microbes (microbicidal) or prevent their growth (microbistatic)
- antibiotic: term used to define therapeutic drugs to treat bacterial infections
- majority of antimicrobials are natural products that certain bacteria and fungi produce and send
outside of their cells – only very few synthetic antibiotics
- antimicrobial resistance: ability of microbes to grow in presence of a drug that would normally kill or
limit their growth
How does drug susceptible bacteria become drug resistant?
- use of antibiotics in clinical settings can have two effects: 1) kill S pathogens 2) select mutant resistant
strains to drugs used (side effect)
- emergence of antibiotic resistance is a consequence of improper use of antibiotics, which selects for
antibiotic resistant strains of bacteria
- if don’t take the antibiotic at proper time, will not have a high enough concentration to kill the
bacteria, and this will select for R bacteria
- multidrug resistance (MDR): ability of a living cell to show resistance to a wide variety of structurally
and functionally unrelated compounds
- selective pressure is the use of an antibiotic
- dissemination: entire population of bacteria become resistant from a single bacterial mutation
- can occur due to point mutations, that can lead to missense mutations (wrong amino acid and thus
different protein), nonsense mutations (encode stop codon), and silent mutations (encodes same amino
acid se